Delphi DataSnap REST problem with TJSONObject

Hi Experts!

I have been using DataSnap REST for some weeks but I have problems understanding some concepts related to TJSONObject and how these data are sent.
I have three related questions.
I consider a simple class:

TMyclass = class
  private
    [JSONName('name')] // invio
    Fname: string;
    [JSONName('surname')] // invio
    Fsurname: string;
    [JSONName('mytext')] // invio
    Fmytext: string;

    procedure Setname(const Value: string);
    procedure Setsurname(const Value: string);
    procedure Setmytext(const Value: string);
  public
    property name: string read Fname write Setname;
    property surname: string read Fsurname write Setsurname;
    property mytext: string read Fmytext write Setmytext;
  end;
  
.....

procedure TMyclass.Setname(const Value: string);
begin
  Fname := Value;
end;

procedure TMyclass.Setsurname(const Value: string);
begin
  Fsurname := Value;
end;

procedure TMyclass.Setmytext(const Value: string);
begin
  Fmytext := Value;
end;  

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.....

In my code I have something similar to:

Procedure TMain.Send_JSON;
var
   VJSONObject: TJSONObject;
   VMyclass:TMyclass;
begin
   VMyclass:=TMyclass.Create;

   VMyclass.name:='John';
   VMyclass.surname:='Ace';
   VMyclass.mytext:='';

   VJSONObject:=TJson.ObjectToJsonObject(VMyclass);
   //...
   
   RESTClient1.ResetToDefaults;
   RESTRequest1.ResetToDefaults;
   RESTResponse1.ResetToDefaults;
   RESTClient1.BaseURL:='http://111.222.333.444:8080/datasnap/rest/mypath';
   RESTRequest1.Timeout:=RESTRequest_Timeout;
   
   RESTRequest1.Resource:='/MyParam'; 
   RESTRequest1.Method:=TRESTRequestMethod.rmPOST; 
   RESTRequest1.AddBody(VJSONObject.ToJSON, ContentTypeFromString('application/json'));
   //...
   RESTRequest1.Execute;
   //...
end;

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[First question]
When I send this JSON:
         {"name":"John","surname":"Ace","mytext":""}
i don't want to have:
"mytext":""
in the JSON.

[Second question]
I don't know a way to insert a JSON array like this:
{"name":"John","file": [{"name_file":"myfile1.txt","dir_file":"C:\mydir"},{"name_file":"myfile2.txt","dir_file":"C:\mydir2"},...]}

[Third question]
I am looking for a method to manipulate the:

VJSONObject.ToString

before insert in the:

RESTRequest1.AddBody(VJSONObject.ToJSON,...

but I couldn't find it. I search something like:

  VJSONObject := Json.StringToJsonObject(VJSONObject.ToString);

I have a lot of problems because there is no documentation on this part.
Does anyone have a solution?


Working with RAD Studio Tokyo 10.2.3